Is the pope similar to the high priest of the Old Testament?
The short answer
Similar, though not identical. The high priest offered the greatest sacrifices and led God's people on earth. Christ is our high priest who offered himself and the head of God's people, but he left Peter as his visible representative; the pope, Peter's successor, resembles the high priest as earthly head of God's people.
The pope's role resembles, but is not identical to, the Old Testament high priest's. The high priest offered the greatest sacrifices, as on Yom Kippur, the Day of Atonement, and was the earthly leader of God's people.
Christ is our high priest as regards sacrifice, having offered the great sacrifice of himself (see Hebrews 7–10), and he is the ultimate head of all God's people. But he left Peter here as his visible representative during his absence. The pope, as Peter's successor, is thus like the high priest in being the earthly head of God's people.